1. Field of the Invention
The present invention relates to a hard disk drive. More particularly, the present invention relates to a head stack assembly (HSA) of a hard disk drive having a swing arm and a crash stopper that limits the rotation of the swing arm. The present invention also relates to a method of assembling such a hard disk drive.
2. Description of the Related Art
Hard disk drives (HDDs) serve as auxiliary memory devices for computers, MP3 players, and mobile phones. To this end, an HDD has a head stack assembly (HSA) that includes a swing arm, and a magnetic read/write head supported by the swing arm for recording data on a disc or reading data from the disc. The swing arm of the HSA is mounted on a base so as to be rotatable in clockwise and counter-clockwise directions relative to the base. A voice coil motor rotates the swing arm to position the magnetic head over a desired location on the disk (i.e., over a desired track) onto which data is to be recorded or from which data is to be reproduced. The HSA also has a crash stopper that limits the rotation of the swing arm to a predetermined range.
FIG. 1 is a perspective view of a conventional hard disk drive 10, and FIG. 2 is a plan view of another conventional hard disk drive 30.
Referring to FIG. 1, the conventional hard disk drive 10 includes a base 11, a disc 12 rotated at a high speed by a spindle motor mounted to the base 11, an HSA 15, and a voice coil motor (VCM) block 20. The HSA 15 includes a swing arm mounted to the base 11 so as to be rotatable, a head slider comprising the magnetic read/write head mounted on one end of the swing arm, and a voice coil support 17 integral with the other end of the swing arm. A voice coil motor, made up of the (VCM) block 20 and a voice coil (not shown) wound around the voice coil support 17, rotates the swing arm of the HSA 15 in clockwise and counterclockwise directions.
The VCM block 20 includes an upper yoke 21 and a lower yoke 23, which are respectively disposed above and below the voice coil support 17 of the HSA 15, and a pair of magnets (not shown) which are respectively attached to inner surfaces of the upper yoke 21 and the lower yoke 23. The VCM block 20 is mounted to the base 11 by a pair of screws 25 and 26. Also, the VCM block 20 also includes a crash stopper 27 that limits the rotation of the swing arm of the HSA 15 in the clockwise direction. That is, the coil support 17 of the HSA 15 bumps against the crash stopper 27 when the HSA 15 rotates a certain amount in the clockwise direction, whereby the crash stopper 27 prevents the swing arm from rotating further in the clockwise direction.
The VCM block 20 is mounted to the base 11 as follows. First, the crash stopper 27 is inserted between and attached to the upper yoke 21 and the lower yoke 23, and one side of the VCM block 20 is fixed to the base 11 using the screw 25. Next, the VCM block 20 is rotated in a counterclockwise direction about the screw 25 until the other side of the VCM 20 is disposed over the base 11. Then, the other side of the VCM block 20 is fixed to the base 11 using the screw 26. Obviously, the base 11 must be a so called ‘flat type’ of base, i.e., must have a flat upper surface, to facilitate this method of mounting the VCM block 20 to the base 11. However, the flat type of base 11 is relatively thick. Accordingly, it can be difficult to incorporate the conventional hard disk drive 10 into current electronic apparatuses that tend to be smaller and thinner than those in the past.
Referring to FIG. 2, the conventional hard disk drive 30 includes a base 31, a disc 32 rotated at a high speed by a spindle motor mounted to the base 32, an HSA 35, and a VCM block 40. The base 31 is a so called ‘bowl type’ of base having a concavity in which the disc 32, the HSA 35, and the VCM block 40 are received. The conventional hard disk drive 30 also includes a main circuit board (not shown) mounted to the underside of the base 11, a flexible printed circuit (FPC) 42 electrically connecting the main circuit board to the HSA 35, and FPC bracket 45 that fixes and end of the FPC 42 to the base 31. The HSA includes a swing arm supported by the base 31 so as to be rotatable about an axis 36, and a head slider 39 (comprising the magnetic read/write head) attached to an end of the swing arm. A VCM, made up of the VCM block 40 and a voice coil (not shown), rotates the swing arm about axis 36 in clockwise and counterclockwise directions.
The conventional HSA 30 also has a crash stopper 47 that limits the rotation of the swing arm of the HSA 35 in the clockwise direction. The crash stopper 47 is attached to the FPC bracket 45. A protrusion 37 of the swing arm of the HSA 35 bumps against the crash stopper 47 when the HSA 35 rotates a certain amount in the clockwise direction, whereby the crash stopper 47 prevents the swing arm of the HSA 35 from rotating further in the clockwise direction.
However, the range of rotation of the swing arm of the HSA 35 can be set erroneously by the crash stopper 47 because of tolerances in the shape or mounting of the FPC bracket 45 to which the crash stopper 47 is attached. In this respect, the distance S2 between the axis of rotation 36 of the swing arm and the terminus of the protrusion 37 is much smaller than the distance S1 between the axis of rotation 36 of the swing arm and the head slider 39. Accordingly, even slight errors in the location of the crash stopper 47 relative to the terminus of the protrusion 37 can translate into large errors in the range of rotation of the swing arm of the HSA 35. In particular, slight errors in the location of the crash stopper 47 relative to the terminus of the protrusion 37 can prevent the swing arm of the HSA 35 from rotating over its entire designed range of rotation. In this case, the magnetic read/write head will not be able to record data onto or read data from a portion of the disk 32